A luminaire generally includes a light source, such as a fluorescent bulb, radiating into a light guide which directs the light in a predetermined direction, such as downward. These luminaires are used to provide a more uniform light distribution than conventional light systems and alleviate glare in applications such as office space, boardrooms, and customer service centers.
Prior art luminaires have centered light in front of the light guide which causes specific areas of high brightness. This high brightness area causes glare as the light reflects from shiny surfaces such as magazine pages, computer screens, table tops, etc. Large reflective baffles have been used to reflect light into a specific distribution pattern but the bright image of the bulb is still present creating intense glare. Textured panels or structured panels have been used to hide or mask the bulb image. However, these prior art systems have not been effective in hiding the bulb image or in effectively controlling the light distribution.
A need exists, therefore, for a luminaire that effectively hides the bulb image, creates well defined light distributions, is light weight relative to solid optical waveguides, and which can be inexpensively produced.
A luminaire and method are provided, in one embodiment, comprising a light source, a plurality of prisms, such as linear prisms, for redirecting light from the light source in a predetermined direction, and a reflector for redirecting light from the light source toward the plurality of prisms.
In one embodiment, each of the linear prisms has a longitudinal axis and the light source has a longitudinal axis, the longitudinal axes of the linear prisms being substantially parallel to the longitudinal axis of the light source.
Each of the plurality of prisms has an included angle, which can vary as a function of the distance from the light source. For example, the angle can vary stepwise or continuously. In one embodiment, each of the plurality of prisms adjacent the light guide has an included angle in the range of between about 35 and 45 degrees. In another embodiment, the included angle is substantially uniform among the prisms.
In one embodiment, the plurality of prisms are substantially horizontal and the reflector is angled with respect to a horizontal plane. The plurality of prisms can be configured so as to form a curve.
A luminaire is also provided which includes a light source, a light guide that receives light radiating from the light source, a plurality of prisms adjacent the light guide for redirecting the light from the light guide substantially perpendicular to a longitudinal axis of the light guide, and a plurality of prisms adjacent the light source that control the spreading of light along the longitudinal axis of the light guide. In one embodiment, the light guide is triangular shaped. In another embodiment, the light guide is rectangular shaped.
A redirecting device can be positioned adjacent the light source for redirecting light rays into the light guide. The longitudinal axis of the luminaire can be tipped relative to a horizontal plane.
The luminaire can include the plurality of prisms adjacent the light guide spaced apart from one another. In one embodiment, the plurality of prisms are spaced about 0.51 millimeters (0.020 inches) apart. In another embodiment, the plurality of prisms are spaced apart in the range of between about 0.025 and 3.175 millimeters (0.001 and 0.125 inches).
A luminaire is further provided which includes a light source, a light guide that receives light radiating from the light source, and a plurality of prisms adjacent the light guide that redirect the light from the light guide substantially perpendicular to a longitudinal axis of the light guide. In one embodiment, the prisms are formed from a single sheet of material into an integral tube.
The luminaire can further include a plurality of prisms adjacent the light source to control the spreading of light along the longitudinal axis of the light guide. Bending grooves or surfaces, for example, living hinges, can be provided in the sheet of material for forming the tube. The tube can include a reflective surface on an inside, end surface to prevent the light rays from leaving through the end of the light guide.
A closed rectangular, triangular, or any polygon cross-section optical tube can also be formed by providing appropriate bending grooves or surfaces.